i will be running 70' of sec across a basement to my panel.
my question is do i need to treat the panel as a sub panel and treat the disconnect as the main panel. (i went from the meter to an outside disconnect then to the panel in the middle of the basement.)
Re: service entrance cable from disconnect to panel
You don't treat it as the main panel, it is the main panel. The first means of disconnecting of the incoming electric is the main service equipment and is covered in Article 230, all circuits out of that panelboard are either feeders or branch circuits. You are describing an installation where you are going from the service equipment to a downstream panelboard located in the basement.
You are certainly correct that this disconnect should be a fusible one. I think we all assume that it is.
It would have to be fusible to comply with 230.91 which requires the overcurrent protection to be part of or be immediately adjacent of the service disconnect.
This is in addition to 230.70(A)(1) which is the section that requires the service disconnect to be nearest the point of entrance of the service conductors.